Cement and screw reconstruction for Rand type II bone defects during total knee arthroplasty: a retrospective clinical and radiographic evaluation

Abstract

Objective

To investigate the clinical and radiographic results of cement and screw reconstruction for bone defects during total knee arthroplasty(TKA).

Methods

From September 2014 to September 2019, 38 patients with Rand type II bone defects who underwent the screw plus cement technique during primary TKA were included in this study. The clinical results were evaluated via the Knee Society Knee Scale (KSKS), Knee Society Function Scale (KSFS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and range of motion (ROM). The hip–knee–ankle angle (HKAA), femorotibial angle (FTA), and radiolucent lines were assessed radiologically.

Results

Thirty-five patients were followed up for an average of 92.6 months (60–120 months). At the last follow-up visit, the KSKS, KSFS, WOMAC score, and ROM were significantly improved. The HKAA and FTA were corrected postoperatively. In 3 patients, a nonprogressive radiolucent line measuring approximately 1 mm was observed at the interface between the host bone and the cement at 3, 6 and 12 months after surgery, with an incidence of 8.3%, No radiolucent lines were found around the screws and no infection, fracture or prosthesis loosening occurred at the last follow-up visit.

Conclusion

Cement and screw reconstruction for Rand type II bone defects during TKA achieved satisfactory clinical and radiological results and solid fixation. This could be considered an economical and practical method to repair mild and moderate bone defects in primary TKA patients.

Introduction

Total knee arthroplasty (TKA) has become the standard surgical treatment for end-stage osteoarthritis of the knee. Recent studies [1] have shown that the subchondral bone phenotype and inflammatory phenotype are associated with the progression of joint space narrowing, osteophytes and sclerosis at 24 months, along with subsequent TKA at 108 months. Severe varus knee deformities are frequently undiagnosed because of insufficient attention, although the robot-assisted system significantly improved alignment precision and prosthesis placement for patients with severe preoperative deformities, highlighting its superior efficacy in complex cases [2]. Bone reconstruction may be necessary to restore joint stability. Common surgical repair techniques for tibial bone defects include tibial bone osteotomy, lateral placement of the tibial plateau and contraction of the medial tibial plateau [3]. However, although the abovementioned techniques are effective for the repair of tibial plateau bone defects, they can weaken the tibial plateau to some extent. Moreover, after osteotomy, the lateral plateau should be above the fibular head to avoid a low joint line. Excessive lateral placement of the tibial prosthesis may affect the mechanical alignment of the lower limb. Therefore, surgical treatment is considered auxiliary whereas reconstruction is essential. Bone defects are typically repaired with cement and autologous or allogeneic bone [4, 5], screws combined with bone cement [6], porous metal pillars [7], and metal augments. Metal augments [8–10] are associated with relatively low risks of bone nonunion and platform collapse despite potential wear and corrosion and can be used to repair bone defects larger than 10 mm. Although allograft bone can be modified into various geometric shapes according to the size and shape of bone defects, it is associated with complications such as poor healing, disease transmission and immune rejection. Currently, autogenous bone grafting [11, 12] is the main method for treating bone defects, although it is associated with complications such as bone resorption, collapse, nonunion and infection. Panegrossi et al. [13] suggested that bone cement fixation is suitable only for peripheral defects occupying less than 50% of the bone surface and < 5 mm deep. Recently, some scholars have used screws combined with bone cement for bone defects larger than 5 mm and have reported good clinical effects [14], Compared with porous metal pillars⁷ and metal augments, screw plus bone cement fixation is quick, economical, bone preserving, time-saving, and easily adaptable for all sizes of defects.

However, reports on the medium- and long-term effects of this procedure are rare. Therefore, we retrospectively studied the clinical data of 38 patients with Rand type II bone defects of the medial tibial plateau who underwent screw plus cement repair in our department from September 2014 to September 2019.

Methods and materials

Clinical data

This study was approved by the Medical Ethics Committee of our hospital. From September 2014 to September 2019, 38 genu varus patients with Rand type II bone defects who underwent primary TKA with screws and cement were included in this study. Proximal tibial bone defects are classified using the Rand classification [15](Table 1): Type I, < 50% unilateral tibial plateau involvement and a defect depth < 5 mm; Type II, 50% ~ 70% unilateral tibial plateau involvement and a defect depth of 5 ~ 10 mm; Type III, 70% ~ 90% unilateral tibial plateau involvement and a defect depth >10 mm; and Type IV, >90% unilateral tibial plateau involvement and a depth of the defect >10 mm. Each type is divided into 2 subtypes: a, the tibial cortex is complete; b, the tibial cortex is defective.

Table 1.

Classfication of bone defects

Type	Single Condylar Involvement(%)	Depth(mm)
I Minimal	< 50	< 5
II Moderate	> 50 and < 70	5–10
III Extensive	> 70 and < 90	≥ 10
IV Cavitary
(a)Intact peripheral rim	> 90
(b)Dificient peripheral rim	> 90

Considering the social and economic benefits, Rand type II tibial bone defects require repair with screws and cement at our institution. Among these 38 patients, 1 was lost to follow-up, 1 had incomplete data, 1 died from a traffic accident, and the final 35 patients (35 knees) who were followed for an average of 92.6 months were included. The demographic data of the 35 patients are showed below (Table 2).

Table 2.

Demographic data(35 cases)

	value
age(year, ± S)	65.30 ± 7.15
female(number, ratio)	24(68.6%)
BMI(kg/m2, ± S)	22.12 ± 3.43
Follow-up(month, ± S)	92.6 ± 23.1

BMI body mass index

The mean age of the patients, which included 24 women and 11 men, was 65.30 ± 7.15 years, with a height of 1.67 ± 0.10 m and a body mass index (BMI) of 22.12 ± 3.43 kg/m². The follow-up time was 92.6 months (60–120 months). All patients were diagnosed with degenerative osteoarthritis of the knee with a varus deformity. The prostheses used were as follows: Gemini II (LINK, Germany) in 17 knees, Attune (Depuy, USA) in 10 knees, and A3 (AK Medical Ltd., Beijing China) in 8 knees. All prostheses were fixed with bone cement. Posterior stabilized prostheses were selected for all the patients because of the surgeon’s preference. No constrained condylar knee prosthesis was used, and a 4 cm tibial extension stem was implanted in two patients in the A3 group. None of the patients underwent patellar replacement; however, patellar reshaping was performed for patients with severe lateral patellofemoral joint degeneration due to potential restrictions in postoperative knee function [16]. The screws were 6.5 mm in diameter and 10–30 mm in length.

Surgical procedure and postoperative management [14]

The operation was performed by the same senior surgeon for all patients. A medial incision was made in the knee via the medial parapatellar approach to expose the knee cavity and remove the osteophyte. The tibia and femur were sequentially dissected via the measuring osteotomy technique, after which flexion and extension were tested. The soft tissue was balanced via conventional methods. The tibial platform was osteotomized to a depth of 8–10 mm below the lateral platform cartilage. If the space was narrow, the size of the tibial platform was first reduced by 2 mm; as a result, bone defects can be partly removed by performing bone resection and downsizing and lateralizing the tibial component. A sterilized steel ruler was used to measure the depth, length and width of the defects. The number of screws was determined according to the size of the defect. Holes were drilled to allow the insertion of 1–3 cancellous bone screws measuring 6.5 mm in diameter. For bone defects with a defect area less than 20%, the use of 1 screw achieved the greatest stability; for those with a defect area between 20% and 50%, 2 screws achieved the greatest stability. and for those with a defect area larger than 50%, 3 screws achieved the greatest stability. Screws were used in moderation for different defects; more is not always better. Ozcan [17] managed a minimum of 2 screws for the defects involving two quadrants and a single screw for smaller defects. The length of the screw varied from 30 to 45 mm, which was similar to our procedure. Screws were inserted perpendicular to the osteotomy surface, and long screws were selected because they were considered to provide greater stability. The most common screw length was 10–30 mm, and the screw tail is flat to the osteotomy surface. Small holes were drilled (1 mm wide and 1 mm deep) in the surface of the bone defect to promote the penetration of bone cement [18]. After the tibial platform surface was cleaned, the bone cement was filled in the bone defect area around the screws and the tibial prostheses were installed (a 4 cm extension rod was used for two patients with A3 prostheses). Intra-articular injection of 1000 mg of vancomycin after arthrotomy closure provided a therapeutic intra-articular concentration while avoiding systemic toxicity for patients with a high risk of preoperative infection [19]. Afterwards, the excess bone cement was removed. Multimodal analgesia was administered as the standard approach for perioperative pain control in TKA [20]. All the patients were able to bear their partial weight while walking with two crutches on the second day after surgery. The rehabilitation plan was the same as that for all patients who undergo primary TKA.

Evaluation index of clinical efficacy

The Knee Society Score (KSS) system [21], which includes the Knee Society Knee Scale (KSKS) and the Knee Society Function Scale (KSFS) was adopted. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was also calculated [22]. The KSS and WOMAC scores were recorded before and after surgery. The length, width and height of the defect were measured intraoperatively, the proportion of involvement of the unilateral tibial plateau was calculated, and the number and length of screws used during the operation were recorded.

Imaging measurements

The hip–knee–ankle angle (HKAA) [23] of both legs was measured on full-length standing radiographs before and after the operation and at the last follow-up. Complications such as platform collapse, prosthesis loosening [24] and osteolysis were recorded. Anteroposterior and lateral radiographs were obtained at each follow-up visit to assess the presence or absence of implant loosening and to determine the Knee Society Scores [24].The Knee Society roentgenographic evaluation system of Ewald [24] and the modified radiographic evaluation system of Bach [25] were used to determine and assess the radiolucent lines.

Statistical processing

SPSS 19.0 statistical software was used for statistical processing, measurements are expressed as X ± S values, normality tests were performed before conducting the t tests in our study with the Shapiro‒Wilk test, and paired sample t tests were used. The chi-square test was used for counting data, and two-tailed p values < 0.05 indicated statistical significance.

Results

Clinical effects

Among the 38 patients, 1 patient was lost to follow-up, 1 patient had incomplete data, and 1 patient died because of a traffic accident. Finally, 35 patients were followed up for 92.6 months (60–120 months). There were 13 inclusive and 22 noninclusive tibial plateau defects. The defect depth was 7.84 ± 3.12 mm, and the defect area accounted for 57.5%±17.6% of the ipsilateral tibial plateau.The tibial plateau bone defects were classified as type II bone defects according to the Rand classification; 13 knees were treated with 3 screws, 15 knees were treated with 2 screws, and 7 knees were treated with 1 screw. There were 20 patients with 15 mm screws, 26 patients with 20 mm screws, 20 patients with 25 mm screws, and 10 patients with 30 mm screws. Varus deformity and/or flexion contracture deformity were corrected in all patients, and all patients were able to bear their partial weight with crutches on the first day after surgery. The mean postoperative KSKS score was 89.8 ± 5.1(range, 79.3 to 98.8) (Table 3). The mean postoperative KSFS score was 90.2 ± 6.2(range, 77 to 97). The mean postoperative WOMAC score was 7.4 ± 3.5(range, 1.2 to 14.6), as shown below (Table 3).

Table 3.

Imaging follow-up results

	Pre-operation	Post-operation	t	P
KSKS	21.7 ± 6.8	89.8 ± 5.1	4.64	< 0.05
KSFS	25.3 ± 7.1	90.2 ± 6.2	5.13	< 0.05
WOMAC	72.4 ± 4.6	7.4 ± 3.5	8.36	< 0.05

KSKS knee society knee scale, KSFS knee society function scale

Compared with those before the operation, the KSKS score, KSFS score and WOMAC score significantly improved after the operation (P < 0.05); however, there were no significant differences between the postoperative score and the last follow-up score, as shown below (Fig. 1). The range of motion increased significantly (P < 0.05).

Fig. 1.

The comparision of KSKS, KSFS and WOMAC score. ***P < 0.001 and ns = not significant.

Imaging results

The mean HKAA on early postoperative radiographs was 178.24°±1.25° (range, 174.1° to 182.4°). The mean FTA on early postoperative radiographs was measured as 184.51°±1.38° (range, 181.0° to 188.0°), as shown below (Table 4).

Table 4.

Clinical follow-up results( ± S)

	Pre-operation	Post-operation	t	p
HKAA	160.13°±8.72°	178.24º±1.25°	5.12	< 0.05
FTA	165.62°±9.14°	184.51º±1.38°	6.37	< 0.05

HKAA Hip-knee-ankle angle, FTA tibiofemoral angle

Compared with those before surgery, the HKAA and FTA angles significantly improved postoperatively (P < 0.05). There was no significant difference in the HKAA or FTA angle between the last follow-up and the postoperative results (P > 0.05) as shown below (Fig. 2).

Fig. 2.

The comparision of HKAA and FTA angles. ***P < 0.001 and ns = not significant

At 3, 6 and 12 months after surgery, there was a nonprogressive radiolucent line approximately 1 mm between the host bone and the cement, the incidence rate was 8.6%, and no change was noted at the last follow-up. Aseptic loosening, infection, fracture and osteolysis did not occur in any of the patients, and no patients underwent revision surgery.

Typical cases

Figures 3 and 4.

Fig. 3.

Screw-and-cement technique for uncontained tibial bone defects. A Bone defect was debrided as indicated by the yellow arrow. B Holes were drilled in the area of the bone defect. C The depth of the screws was measured. D A screw was placed perpendicular to the tibial osteotomy. E The two screws were placed with the top of the screws just below the cutting surface of the tibia. F Bone cement was placed on the surface of the resected tibia, around the screws and in the area of the bone defect where the blue arrow points

Fig. 4.

Preoperative and postoperative radiographs of a 67-year-old female patient. A/B. Preoperative radiographs showing a medial tibial plateau defect in both knees. C/D. Postoperative standing X-ray revealing defects in 70% (9 mm) and 60% (8 mm) of the right and left tibial plateaus, respectively, which were filled with three and two screws combined with bone cement, respectively, and the right tibial prosthesis plus a 4 cm extension stem. There were two vertical screws and one oblique screw placed in the right knee and two oblique screws in the left knee. E/F. One year after surgery, the radiographs reveal that the prosthesis is in a good position, and there is a radiolucent line in zone 5 between the host bone and the cement without knee pain or joint instability, continue observation. G/H. Five years after surgery, the prosthesis is still in a good position, the radiolucent line is not progressive; aseptic loosening, joint instability, fracture and osteolysis have not occurred; and there has been no need for revision surgery

Discussion

In this study, we report the clinical and imaging results of a screw plus cement repair technique for varus knee deformity and Rand type II tibial plateau bone defects. The midterm Knee Society score, WOMAC score, and ROM were satisfactory; all screws were considered stable; there were no progressive radiolucent lines between the cement and host bone; and at an average of 92.6 months after the procedure, there were no cases of implant failure, which could have led to prosthesis revision on account of aseptic loosening of the tibial tray. Harnma [18] emphasized the viability of the screw‒cement construct for managing uncontained tibial defects up to 20 mm during TKA and reduced the overall procedural costs without compromising implant survival, which was consistent with the results of our study.

Currently, the optimal treatment for tibial plateau bone defects during TKA has not been established. The severity of the tibial plateau defect can be reduced by increasing the extent of the osteotomy and narrowing the tibial platform as much as possible; however, surgical treatment of bone defects is considered an auxiliary method, although the repair of bone defects is challenging, especially for moderate and severe bone defects in the tibial plateau. Metal augments [7, 26] are associated with relatively low risks of bone nonunion and platform collapse and are often used to repair bone defects larger than 10 mm. Metal sleeves or cones [7, 27, 28] are mostly used in the repair of severe bone defects, such as knee revision surgery, and are more expensive. Tang [7] used porous metal pillars to repair bone defects in the medial and lateral tibial plateaus and reported good short-term clinical and radiological effects; however, these methods are relatively expensive, and their long-term efficacy still needs to be evaluated. Allogeneic bone grafts can be modified into various geometric shapes according to the shape and size of the platform defect. However, owing to adverse factors such as poor healing, disease transmission and immune rejection, autografts [9] are currently used in most bone grafting methods. Kharbanda [29] reported that the main advantage of an autograft is the bone reserve, which is crucial for revision surgery. In their study of 675 patients with varus knees who underwent primary TKA, 54 patients were found to have bone defects, 48 of whom had defects extending deeper than 5 mm and involving 25‒40% of the platform. These patients underwent autologous bone graft placement and screw fixation; the other 6 patients who had defects extending deeper than 25 mm and involving more than 40% of the platform underwent titanium mesh placement combined with compression bone graft repair. The average follow-up duration was 7.8 years, and the results were satisfactory. Chong [9] reported that bone defects larger than 10 mm and involving less than 30% of the platform do not need extension stems or metal augmentation and that better clinical results may be obtained through the use of autologous bone. However, this technique is associated with complications such as bone resorption, collapse, bone nonunion and infection.

Panegrossi et al. [13] suggested that simple bone cement fixation is only suitable for peripheral defects occupying less than 50% of the bone surface and extending to a depth < 5 mm. In recent years, some scholars have applied screws combined with bone cement to varus knees with bone defects larger than 5 mm and reported good clinical effects [14]. Biomechanical studies [6, 30] have shown that screws and cement are suitable for 5–15 mm bone defects and that longer screws may not achieve better stability, but thicker screws can reduce the stress on the surface of tibial defects and achieve better stability. The effects of screws and bone cement are better than those of bone cement alone, but the use of more screws does not result in better results. Screw thickness, but not length, had the greatest effect on tibial plateau stress, and screws with a diameter of 6.5 mm are better than screws with diameters of 5 mm and 3.5 mm. Zheng [31] reported that for bone defects with a 12% defect area and a 12-mm defect depth, the use of 1 screw achieved the greatest stability; for those with a 15% defect area and a 20-mm defect depth, 2 screws achieved the greatest stability. These findings are consistent with our results. Moreover, one or two screws perpendicular to the upper surface of the tibial plateau can achieve better stability than screws parallel to the proximal cortical bone of the tibia. If two screws cannot be inserted vertically, one vertical screw and one oblique screw are acceptable [32]. The screws used in this study were cancellous bone screws for the lower extremity with a diameter of 6.5 mm, and the screws were oriented perpendicular to the osteotomy platform of the tibial plateau, providing greater biomechanical stability.

After 20 years of follow-up examinations, Michael [14] reported that compared with TKA fixation without bone defects or screws, tibial plateau screw fixation might decrease the plateau bone mass because of the increased bone osteotomy volume, but there was no difference in the long-term loosening rate compared with TKA fixation without bone defects or screws. The long-term loosening rate of prostheses was greater when the depth of the defect repaired by screws and cement was greater than 20 mm and the range of platform involvement was nearly 100%. Therefore, only Rand type II tibial plateau bone defects should be fixed with screws and cement, and Rand type III and IV defects larger than 10 mm should undergo repair with metal augments. Zheng [33] followed up 40 cases of varus knees and reported that the screw and cement technique was simple and safe for repairing tibial plateau bone defects and that the number of screws used was related to the depth and area of the tibial plateau bone defect. A biomechanical study [31] revealed that more screws do not always yield better results. The number of screws used in the operation depends on the defect area and is usually 2‒3.

Moreover, Berend [14] reported that radiolucent lines were present in 13.7% and 6.4% of patients in the screw group and the nonscrew group, respectively. At 3, 6 and 12 months after surgery, there was 1 case of a nonprogressive radiolucent line measuring approximately 1 mm at the interface between the tibial plateau and the bone cement; the incidence rate was 8.6%, and no progression was detected at the last follow-up visit. Knee joint function recovered well after screw and cement fixation. Zhang [33] reported that the average knee joint function score of 34 patients (40 knees) increased from 43.33 ± 6.61 before surgery to 92.15 ± 4.64 after 2 years of follow-up, and the postoperative effect was good. The 35 patients in this study were followed up for an average of 92.6 months, and the knee joint score and function score increased from 21.7 ± 6.8 and 25.3 ± 7.1 before surgery to 89.8 ± 5.1 and 90.2 ± 6.2, respectively. The WOMAC score ranged from 72.4 ± 6.4 before surgery to 7.4 ± 3.5 at the last follow-up visit. However, the clinical effects and radiographs did not significantly differ between the early postoperative period and the last follow-up, which was similar to the result of a recent study [17]. Therefore, the screw and cement technique achieved acceptable clinical and radiological results in total knee arthroplasty combined with medial tibial plateau bone defect repair.

Dorr [34] proposed that the tibial extensional stem should be used to disperse stress on large tibial bone defects. In a finite element study, Frehill [35] found that the use of an extension stem can reduce stress on the cancellous bone used in the repair of large defects and that it is not necessary to use an extension stem for small defects. However, the specific application of extended stems in large areas has not been specified. Ryu [8] reported that in 74 patients (80 knees) who were followed up for more than 10 years, 5 mm metal augments without a tibial extensional stem can also achieve good clinical and radiological effects. Based on a finite element analysis, Zheng [31] proposed that a tibial extension stem should be selected to disperse the stress on the tibial plateau when more than 4 screws are used to repair relatively large bone defects. To determine whether the use of a tibial extension stem would lead to osteoporosis or bone graft absorption under the tibial platform due to stress occlusion, Kwon [36] conducted a finite element study and reported that when a short stem was applied, the maximal principal strain on the trabecular bone was approximately 8% and 20% lower than when a long stem was applied or when no stem was applied, respectively, suggesting that short stem extension of the tibial component could help achieve excellent biomechanical results when performing TKA with a medial tibial bone defect. Alexandru [37] concluded that it is not necessary to use a tibial extensional stem in primary TKA patients with good bone; however, if there is a significant decrease in bone mass, a tibial extension stem is helpful for enhancing the stability and prolonging the life of the prosthesis. In this study, the bone defect depth of the tibial plateau was 7.84 ± 3.12 mm, and the defect area accounted for 57.5%±17.6% of the ipsilateral tibial plateau, all of which were Rand type II bone defects. Two tibial extensional stems were used. No significant difference was found between the HKAA and FTA at the postoperative follow-up visit or at a mean follow-up of 92.6 months (P >0.05). Liu [38] reported that postoperative femur‒tibia mechanical axis (FTMA) correction was significantly greater in the screw‒cement group than in the thick‒liner group; with no statistically significant differences in the Knee Society Clinical Score, range of motion, forgotten joint score, stiffness, myasthenia, joint clicking, or revision rate. These findings also support the use of the screw‒cement construction technique in TKA. Therefore, we concluded that it is not necessary to use a tibial extension stem to repair most Rand type II medial tibial plateau bone defects when the screw plus cement technique is used; however, this technique can be used to disperse the stress on the plateau and reduce the early prosthesis failure rate in patients with severe bone defects, severe varus knees combined with severe osteoporosis, and tibial extension stems of different lengths and diameters.

Considering the social and economic benefits, the screw plus bone cement technique is less expensive than metal augments and porous metal pillars; moreover, it is convenient to perform during the operation and improves stability immediately after the operation, and there is no risk of bone resorption. Compared with autogenous bone and allograft bone transplantation, recovery is faster, and fewer complications occur. After an average of 92.6 months of follow-up, the use of the screw and cement technique during TKA to repair bone defects of the medial tibial plateau achieved satisfactory clinical and radiological results. Therefore, the screw and cement technique is an economical, practical and reliable method for the repair of mild and moderate medial tibial plateau bone defects during TKA.

The limitation of this study was the lack of a control group for comparative studies, mainly because, considering the social and economic benefits, the cement and screw technique is used for most of the Rand type II bone defects of the tibia at our institution. The limitations also included the small sample size because of the rarity of Rand type II bone defects of the tibia at our institution. Owing to the small sample size, no subgroup analysis of prosthesis heterogeneity was conducted. However, the three different implant types are comparable because of their posterior-stable design and similar shapes of the tibial platform. We hope to conduct a large randomized controlled study to further address the unsolved problems of this study in the future.

Author contributions

Conceptualization: Tihui Wang，Hongwei Xu; formal analysis and investigation: Xu Wang, Tihui Wang; writing-review and editing: Tihui Wang，Jinqing Wu; resources: Hongwei Xu，Tihui Wang. All authors read and approved the final manuscript.

Funding

This study was funded by the Natural Science Foundation of Fujian Province, China (2019J01618) and Ningde City Natural Science Foundation (Grant no. 2023J24) .

Availability of data and materials

The datasets generated during and/or analyzed during the current study are not publicly available, but are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The study was conducted in accordance with the Declaration of Helsinki. Ethical approval was obtained from the Affiliated Mindong Hospital of Fujian Medical University Ethics Committee. All participants signed informed consent forms.

Consent for publication

Not applicable.

Clinical trial number

not applicable.

Competing interests

The authors declare no competing interests.